A major problem with standard backward curved and backward inclined impellers utilized in a blower for a standard air handler, fan coils, and furnaces is that the noise and sound is too high to be acceptable to the consumer since these backward curved and backward inclined impellers must operate at a higher speed than a standard blower. To compound the issue, consumers also require significant energy savings over standard blowers.
The typical construction of a high efficiency furnace 10 is shown in FIG. 1. The furnace 10 has an external housing enclosure 12 with an interior volume 14. Several portions of the side walls of the furnace enclosure 12 shown in FIG. 1 have been removed to illustrate the interior components of the furnace. The dimensions of the furnace enclosure 12 are determined to contain all of the component parts of the furnace in the furnace enclosure 12, without the enclosure occupying a significant area in the residence in which the furnace is installed. In contrast, commercial furnaces are typically mounted on the roof of a building or at some other location outside the building where there are no size restraints. Because commercial furnaces with their large capacity are located outside the structures they serve, there is no need to position the component parts of the furnace relative to each other to minimize the size of the furnace enclosure as there is in residential furnaces.
An air inlet opening is typically provided in a side wall or in the bottom of the furnace enclosure. The air inlet opening can be covered by an air filter that allows ambient air in the environment surrounding the furnace enclosure 12 to easily pass through the opening and enter the enclosure interior 14. Alternatively and more frequently, the air inlet opening of the furnace enclosure communicates with a cold air return duct system of the residence. The cold air return duct system channels ambient air from throughout the residence to the furnace enclosure 12.
The furnace enclosure 12 also has an air distribution outlet opening 18. The outlet opening communicates with an air distribution conduit or duct system of the residence in which the furnace is installed. In FIG. 1, the air distribution outlet opening 18 is located at the top of the furnace enclosure 12. The air heated by the high efficiency furnace 10 is discharged to the air distribution conduit system (not shown) through the air distribution outlet opening 18.
In the typical construction of a high efficiency furnace represented in FIG. 1, a primary heat exchanger 22 is located at the top of the furnace enclosure 12 adjacent the air distribution outlet opening 18. A secondary heat exchanger 24 that qualifies the furnace as a high efficiency furnace is located directly below the primary heat exchanger 22.
An air distribution blower 26 that draws ambient air into the furnace enclosure 12 is positioned just below the secondary heat exchanger 24. A motor (not shown) of the blower rotates a fan wheel 28 in the interior of the blower in a clockwise direction as viewed in FIG. 1. This rotation of the fan wheel 28 draws the ambient air into the blower 26 as represented by the arrow labeled (AIR FLOW) in FIG. 1, and pushes the ambient air out of the blower 26 through the secondary heat exchanger 24, then through the primary heat exchanger 22, and then out of the enclosure through the air distribution outlet opening 18.
A typical blower 26 includes a blower housing that contains the fan wheel 28. The typical blower housing includes an exterior or outer wall 32. The outer wall 32 spirals around the fan wheel 28 in the direction of fan wheel rotation.